Chemistry Chapter 1 Scientific method and Data management Chemistry-Matter and Change Glencoe

The Scientific Method ____________________ Is a systematic way of gathering evidence to support ideas and theories that help explain the natural world around us. Steps to the scientific method ____________________ Do some research and form a ___________ A Hypothesis is a _________________based on research and observations. It is what you think the answer to the problem is. A good way of writing a hypothesis is: If…(a cause (independent variable))…then…(an effect (dependent variable)).

Design and conduct an experiment. An experiment should have these three things to be a proper experiment ____________ are things that change. There are always two; The independent variable. Sometimes called the manipulated variable. The experimenter chooses one thing to do differently in the experiment. The dependent variable. Sometimes called the measured or responding variable. This is the data that is being gathered or recorded.

___________ are all other things in the experiment that are kept the same all the time. ____________ is a standard for comparison. It is like a base line or the data at time zero. You will ___________ __________________.

Analyze the Data This includes making graphs and/or calculations. Look for _______ in the data. Parts of a proper graph: (more info to come) Use graph paper and a ruler __________: Dependent vs. Independent Labels ___________: independent – x axis, dependent – y axis _______________: Data range/number of lines, round up to a counting number Smooth line or curve

Draw a conclusion A conclusion is a 5 sentence paragraph that summarizes your investigation. __________________________ Briefly ____________ your experiment. What was the ___________. Give examples of your data as ____________. What was the _________ you found in the data or what does the data _________. Did the data trend ______________your hypothesis.

Theory & Law A ______ is an _________ that has been supported by many, many experiments. It is the most logical explanation of why things work they way they do based on evidence gathered by experimentation. _____________ is a relationship in nature that is supported by many experiments. It is a rule that ________, but doesn’t explain, a pattern in nature and predicts what will happen under special conditions. It is often described with a _________________.

Report your results You will want to put your research out for peer review and/or publish your findings for your peers to evaluate.

Organizing and Graphing Data Data Table Format The proper format for a data table is: Label your independent variable and unit in the first/left-most column Label your dependent variable and unit in the next/right-most column REVIEW: Independent Variable ____________________________ Dependent Variable Data DEPENDENT VARIABLE Label (unit) INDEPENDENT

Titling a Graph A title for a graph should describe what the experiment was _____________ For pie graphs: Titles should name the quantity or thing being divided Student Hair Color For line and bar graphs: Titles should list the dependent variable vs. the independent variable Temperature vs. Time All titles are placed at the ______ of the graph

Creating Line & Bar Graphs Line and bar graphs must: use __________if not constructed on a computer use _______ graduations or scale with even increasing or decreasing increments along the axis - to determine scale for x and y axis, divide range of data (data range is highest value – lowest value) by the number of lines on the axis. Then round the number up to a good counting number like .1, .2, .5, 1, 2, 5, 10, 20, 50… Start your scale near the lowest number.

Calculating the Scale on a Graph Speed (m/s) Water Temperature (°C) 17 25 14 28 11 31 8 34 5 37 For example: The left hand column is the independent variable. The data range should subtract the high data point from the low data point. Data range: Then count the number of lines on the axis you will be putting the scale on. Then divide the range by the number of lines You need to round that number up to one that is easy to count by like 0.1, 0.2, 0.5, 1.0, 2.0, 5.0, 10.0 Start your scale near the lowest number. = 0. = 1.0 17-5=12 22

Metric Conversion scale The Metric System This system is based on powers of 10. It consists of a base unit which is changed by powers of ten when a prefix is added Metric Conversion scale Great Mighty King Henry Died By drinking chocolate milk maybe no one paid attention Giga __ __ Mega__ __ Kilo Hecto Deka base unit deci centi milli__ __micro__ __nano__ __pico (meter) G- M- K- H- D- or dk- m,g,L,s d- c- m- µ- n- p- 109 106 1000 100 10 1 0.1 0.01 0.001 10-6 10-9 10-12

SI System Because units are combined all the time in math equations they often become very large and complex. They are called _________and consist of multiple _______. Scientists tend to abbreviate them. Example: The equation for potential energy is EP= mgh The unit for this using all base units is Kg m2/s2 The abbreviated version of this unit is J for Joule Without standardizing the base units, scientists would never know which mass, distance and time unit was imbedded in the abbreviated unit Joule.

Amount of a specific substance 7 Standard Base Units Quantity Base unit Time Seconds (s) Length meter (m) Mass Kilogram (Kg) Temperature Kelvin (K) Amount of a specific substance mole (mol) Electric current ampere (A) Luminous intensity candela (cd)

Density: A relationship between the mass and volume of an object. Mass: The amount of matter (atoms) an object has. Unit: grams or kilograms Volume: The amount of space an object takes up. Unit: milliliters or cm3 Density: A relationship between the mass and volume of an object. “the amount of matter per volume.”

Density Demo Which is more dense? Why? How could we tell?